This invention has to do with devices adapted for dispensing metered doses of liquid from a container, and containers incorporating such devices, and methods of using them. In preferred embodiments the devices are used in, or adapted for use in, squeezable containers, especially resiliently-shape-recovering squeezable containers. A preferred field of use is that of containers for domestic or household use, containing detergents or other cleaning preparations, fabric conditioners, or liquid foods such as sauces.
Particularly, the invention is concerned with liquid dosing devices of a known kind (referred to below as “the kind described”) having an outlet passage leading to a front discharge opening, past or around a control chamber positioned behind the front discharge opening and having one or more rear control openings to admit a restricted flow of liquid from the container interior into the control chamber. An obturator such as a sliding piston is movable in the control chamber and adapted to advance, during dispensing, under the influence of liquid flowing into the control chamber behind it through the control opening(s). When the obturator has advanced sufficiently it blocks the outlet passage to terminate the dose. Usually the outlet path of the liquid leads from the container interior forwardly past outside the control chamber and then radially inwardly, around (or through) the front peripheral part of the control chamber wall, to in front of the obturator and to the discharge opening. This front part of the chamber wall may have one or more circumferentially-distributed flow openings for this purpose. The discharge opening is typically axial or central at the front of the device. The part of the passage leading immediately to it is desirably defined by a tubular extension, projecting rearwardly towards the obturator and providing a seat against which the front of the obturator rests to block the passage.
See for example our EP-A-0274256 describing how the outside of the tubular extension can also serve to guide the liquid flow rearwardly towards the obturator piston to control its rate of advance.
Devices of the kind described have an advantage, compared with dispensers using a metering chamber adjacent the container mouth, in that the volume dispensed is not swept out or held in the dosing device itself. It is possible to achieve a large dose without a large device.
However there are issues with speed and convenience. Obturators may be slow to recover position, and the dispenser needs to be returned to an upright position to create a new dose or restart the mechanism.
Our WO2005/049477 has two proposals addressing such issues.
One proposal provides a dump valve arrangement at the back of the control chamber. Such a dump valve—also discussed in one version in EP-A-0274256—is operable to close during dispensing—under gravity and/or forward fluid pressure—so that liquid enters the control chamber only through the control opening(s). The dump valve opens after dispensing—under gravity and/or reverse fluid pressure—so that liquid can escape from the control chamber more rapidly than if the only escape route were through the control opening(s).
The second proposal of WO2005/049477, implemented with a resiliently squeezable container, provides a unidirectional valve inhibiting reverse flow in the outlet passage upstream of the obturator's blocking position. On recovery of shape of the container after squeezing out a dose, the movable element of the valve—disclosed as a free annulus or a radial flap—is urged onto its seat by the reverse fluid pressure and prevents liquid from returning to the container interior by way of the outlet passage. Instead it flows back into the container from the control chamber space behind the obturator i.e. through the control opening(s), and/or dump valve opening if present. This speeds return of the obturator to its retracted position so that another dose can be dispensed, and desirably can clear the control chamber and re-initiate the obturator even while the container is inverted (typically, with the front of the dosing device and the discharge opening facing down). Repeated doses can then be dispensed without needing to right the container between doses. The forced retraction of the obturator also draws liquid back out of the discharge opening area (nozzle tube), reducing dripping after dispensing.
We have found that these previous proposals still leave something to be desired in dispensing performance in respect of clean termination of the dose, and in respect of repeated dosing while inverted. The present proposals address these issues independently and in combination, as well as (in preferred embodiments) providing convenient manufacturing solutions for the components concerned.
A first aspect of the present proposals relates to the blocking of flow by the obturator. In a device of the kind described, a surface of the device defining a part of the outlet passage in front of the obturator presents a rearwardly-directed seat, surrounding the outlet passage and engageable by a blocking portion at the front of the obturator in its advanced position, around an annular engagement region, so as to block the outlet passage as mentioned previously. The proposal is that one or both of the surfaces of the obturator and seat comprises a resiliently deformable sealing material, preferably elastomer material, at least around the respective annular engagement region thereof.
By this means we find that we can achieve a marked improvement in dosing performance, so that at the end of a dose, the flow through the discharge opening is cut off suddenly and completely with little or no subsequent dripping.
The seat against which the obturator seals is preferably the annular periphery of a rearwardly-extending tubular formation, typically a cylindrical formation. The corresponding blocking portion of the obturator may be a substantially flat surface, e.g. a substantially flat piston front face. This minimises the contact area and maximises the perpendicularity of the contact surface to the contact movement, reducing wedging and sticking. Desirably the obturator and tubular outlet formation are of relatively rigid plastics material, a the resiliently deformable (elastomeric) material for the seal being provided as a surface covering on one or both of these. We particularly prefer an elastomeric element forming an annulus around the rear edge of a tubular outlet formation, connected by some suitable means (or coated) onto the underlying plastics material of the tubular formation. Desirably the elastomeric element is or includes an annular part with a forwardly-directed annular recess or channel fitting onto the rearwardly-directed annular periphery of the tubular outlet formation.
The resiliently deformable component may be attached to the tubular outlet formation by any suitable means, e.g. interference fit, adhesive, interlock formation or integral moulding such as “two shot” moulding, perhaps with form interlock.
In one preferred embodiment a sleeve of elastomeric covering extends forwardly from the sealing seat, around the tubular outlet formation, to where this formation meets the radially-extending front web of a container closure in which the device is comprised, and the elastomeric member there desirably extends out radially from the sleeve across this web. This radial extension portion may optionally be trapped by engagement by other members of the device, or between the container neck and part of the device, for additional security.
A second aspect of our proposals relates to the feature of a unidirectional anti-reverse valve in the outlet passage, an idea disclosed as such in WO2005/049477. In the present second aspect we provide a unidirectional valve of this type which is resiliently biased against the corresponding seat portion(s), i.e. towards the closed condition. Desirably, this is by means of the valve comprising a flap member of elastomeric material, such as a rubber or thermoplastic elastomer (TPE). The elastomeric valve element may be deformed relative to its free shape when assembled into the device, so that the flap thereof is biased against its counter-surface.
The advantage of this is as follows. As in the proposal of WO2005/049477 above, it prevents reverse flow along the outlet passage when the container—which may still be inverted—recovers its volume after dispensing a dose. This speeds retraction of the obturator, and may enable dispensing of two or more doses without righting the container in between. Additionally, however, the resilient bias of the sealing element to its closed condition resists pressure from the body of liquid in the container when the container is inverted. Dimensions, material and initial bias deformation of the sealing element may be selected so that it will open the outer passage only when a predetermined threshold pressure, corresponding for example to a typical static pressure head associated with a container full of the intended liquid product in the inverted container, is exceeded e.g. by a pressure corresponding to a typical vigorous manual squeeze of the inverted container. Moreover by this simple expedient the valve element takes on the additional function of preventing unwanted preliminary dripping or trickling from the container if there is a delay between inverting it and squeezing it.
As with the first aspect, therefore, the second aspect contributes to achieving a cleanly-defined dose and it is desirable to combine the two aspects of the proposals.
Moreover, since each of the two aspects is preferably embodied using an elastomeric element—a static seal element and a valve flap element respectively—a particularly preferred embodiment of our proposal combines these into a single elastomeric element. It may comprise a central annulus forming the seal on the rear edge of a tubular outlet formation and, radially spaced outwardly therefrom, an integral flap formation (e.g. a continuous annulus, or segment(s) corresponding to one or more circumferentially-localised flow openings) which spans the corresponding portion of the outlet passage.
Desirably the valve operates adjacent (at, adjacent or through) a front periphery of the control chamber and has a sealing edge engageable with a component bounding the outer passage at that point so that in its rest condition it blocks the outer passage at that position.
There may be plural flow openings, e.g. circumferentially distributed between formations which support the control chamber component. These may be controlled by respective portions or segments of the mentioned valve member, or more conveniently by a continuous annular valve flap since this need not be rotationally aligned during assembly.
In a preferred embodiment the valve flap projects generally rearwardly, and is biased radially outwardly against a corresponding opposed sealing region, e.g. on the inside of a component which defines a control chamber and also has supporting structure extending forwardly and/or radially outwardly to mount the control chamber in the container neck, with one or more flow openings at the front of this structure.
The elastomeric element may therefore conveniently comprise a front layer or web with a central rearward sleeve carrying the seal and, spaced radially outwardly from it, one or more rearwardly-projecting sealing skirts constituting the valve flap(s). Such a valve flap may be outwardly radially divergent at least in its free condition. Optionally also a further radially outwardly extending portion of the front web or layer is provided, to be trapped between components of the container closure to hold the elastomeric element securely in position.
By these means, a device otherwise corresponding substantially to the known devices can readily be adapted to significantly improve its dosing performance, reducing dripping or leakage both before and after each dose and/or enabling repeated dosing in the inverted condition if desired.
In other respects, the general conformation of the closure elements (e.g. control chamber, obturator, cap, container) may be as described in the earlier applications acknowledged previously. The device may be provided on a neck at the top of an invertible container. The discharge opening may be directed upwardly, e.g. vertically upwardly, when the container stands upright on its base. The movement direction of the obturator is desirably generally coaxial with the neck, and desirably generally coaxial with the external discharge opening.
In a preferred version, as mentioned above, the outlet passage begins with substantially the entire space surrounding the control chamber—e.g. through a clearance between this chamber (which is typically cylindrical) and a wider container neck in which it is mounted, preferably coaxially—and leads through or around the front edge of the control chamber via one or more circumferentially-distributed openings so as to provide a suitable cross-section of flow, and then inwardly to a central discharge outlet this outlet having said rearwardly-extending tube formation.
In preferred constructions the control chamber and its connection structure are a single moulded unit, connecting to a front cap component of the device which also comprises integrally (or mounts) the discharge outlet formation, and includes means such as a screw thread or snap ribs for securing it onto/into a container neck opening, with the control chamber projecting back inside the container neck with lateral or radial clearance for the outflow of product past it. Desirably an outer cover cap for the discharge opening is included. The cover cap may include a plug closure for the discharge opening. The cover cap may be integrally hinged to the mentioned front cap component. It will be understood that the main web of the front cap component may provide the rear surface against which the radial web of the preferred elastomeric component may lie.
The form of the obturator is not particularly limited, and all of the general and specific options proposed in EP-A-0 274 256 and WO 2005/049477 are available.
The squeezable container may be of any (e.g. well-known) type, shape and material.
The components of the dosing closure device are typically moulded plastics components, joining by snap, press or screw engagements without requiring discrete fasteners. The device is suitable for implementation in mass-produced containers, e.g. for household products or food products. In this respect, TPE is desirable for use as the elastomeric components because many TPEs have high compatibility with household or indeed food use.
The control chamber may or may not be provided with a dump valve of the type described in our above-mentioned earlier applications for further facilitating emptying of the chamber after dosing.
Examples of the present proposals are now described with reference to the accompanying drawings.